Research On Methods Of Dry Ultrasonic Assessment Of Bone Strength

Osteoporosis is a common degenerative disease. The increasing amount of elderly people in our country results in the high possibility of more osteoporosis and bone fractures, which becomes a significant problem in public health. The quantitative assessment of bone strength is the prerequisite and effective method of osteoporosis predicting, for example, DEXA and QCT, which can measure bone density accurately. Howerer, they can not satisfy the demand of the mass screening and long-term dynamic tracking measurement due to their high expense, complex operation and X-ray exposure. The method of quantitative ultrasound bone strength detection is especially suitable for bone status assessment in community and family as it is non-ionizing, inexpensive and simple to use. In view of this situation, the method of dry ultrasonic bone strength measurement was studied, the contents of the study are as follows:1、Establish the method of dry ultrasonic bone strength measurementThe method of dry ultrasonic bone strength with independent intellectual property rights was established based on the theory model of ultrasonic propagation and the principle of quantitative ultrasonic bone strength assessment. A soft and elastic dry coupler was developed, which can compensate the different shape of feet, improve the security of measurement, convenience of operation, the service life and the measurement precision of heel width. A force sensor with high precision was employed to detect the clamping force of heel, which can ensure the consistency of each positioning. Meanwihle, a bidirectional guide rail and shifting device was used for accurate positioning. The electronic technology was applied to realize the ultrasonic signal excitation, receiving, signal conditioning, A/D conversion, storage and uploading PC. Five point three smoothing algorithm was used for ultrasonic signal denoising. Fast Fourier transform and the method of least square fitting were employed to obtain broadband ultrasound attenuation (BUA). The method of threshold and extereme point discrimination were applied to get the feature point of reveiving ultrasound, and then obtain the ultrasound speed (SOS).2、The study of the influence of temperature on dry ultrasonic bone strength measuremnt, and establish the method of eliminating the influence of temperatureFirst, the influence rule of temperature on dry ultrasonic bone strength measuremnt was studied through the experiments. Then, a method of producing warm-air with constant temperature based on PWM loop control was proposed, which can ensure the temperature of ultrasonic transmission channel constant, reduce the influence of temperature on ultrasonic bone strength measurement. Finally, the validity of the method was proved.3、The study of reproducibility and effectiveness of dry ultrasonic bone strength measurementThe reproducibility was evaluated by the CVRMS%of two parameters (BUA and SOS), which is defined as root-mean square average of coefficient of variation. Eleven people were recruited for short-term measurement, and eighteen for medium-term. The short-term CVRMS%were0.30for SOS and4.24for BUA, and the medium-term CVRMS%were0.39for SOS and4.33for BUA. We found that the platform of our dry ultrasonic bone strength measurement achieved the level of the similar device from abroad. The effectiveness was evaluated by correlation analysis between our platform and DEXA device (GE Lunar Prodigy; GE, USA), ultrasonic bone strength device (SONOST-3000). The Pearson correlation between STI of our system and BMD of DEXA was0.793(p<0.01). The Pearson correlation between STI of our system and QUI of SONOST-3000was0.860(p<0.01). The results of correlation analysis showed that the platform of our dry ultrasonic bone strength measurement was effective for bone assessment.4、Preliminary build the evaluation standard of bone strength for adult Chinese peopleThe STIs of500adults were collected from Hefei, Shenzhen and Nanjing based on the method of stratified sampling. Then the methods of mathematical statistics and regression analysis were utilized to build the elementary evaluation standard of bone strength for adult Chinese people, including the curves of men’s and women’s STI with age, the averages of men’s and women’s STI, the standard deviations of men’s and women’s STI. With the method of Bland-Altman, the elementary evaluation standard was estimated; the result showed that it was consistent with the method of DEXA.5、Application research of the system of dry ultrasonic bone strength assessmentFirst, t-test was used for analysing the averages of bone strength in both exercise group and non-exercise group, in which the ages of objects ranged from20-30. Then the influence of exercise on peak bone strength was obtained. The results showed that the peak bone strength of exercise group was significantly higher than that of non-exercise group, so that exercise plays an important role in improving peak bone strength. Second, the method of Bland-Altman was used for analysing the consistency of bone strength of left and right heel, in which20people were recruited. The results showed that the bone strength of left and right calcaneus bone were not significantly different. The bone status can be reflected by only one calcaneus bone.This study has made some meaningful work in the technology of dry ultrasonic bone strength measurement, which is expected to establish a method of bone assessment with high precision, low cost, convenient operation. It has broad applicaion prospects in assessment of adolescents skeletal growth, prevention of osteoporosis in the elderly people, evaluation of fracture risk, and so on.